The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.
Trimarans are vessels with one long, thin hull and two side hulls (amahs) to provide stability and prevent the vessel from capsizing. Because the side hulls are small in comparison to the main hull, the main propulsion machinery is usually fitted into the main hull.
Sea-going trimarans have been manufactured as vehicular ferries, passenger ferries and as warships. In most of these designs, the space above the main propulsion machinery has been used as a cargo space. In the case of vehicular ferries, the space above the engine room is used for the transport of cars and other wheeled vehicles, including trucks and coaches. Due to the required hull configuration, trimarans built to date only have stern loading/unloading arrangements, necessitating that vehicles either turn around on-board, or reverse from the vessel. It is clearly advantageous to make the vehicle space as open as possible and without obstruction, so that trucks, including articulated vehicles, can safely manoeuvre on and off the vessel.
The engine room containing the main propulsion machinery is located below the cargo space and requires access for personnel and services, including ventilation trunking for air, and outlets for engine exhaust.
Generally, the required services have been taken through the deck above and surrounded by a casing mounted on that deck. This structure presents an obstruction to the easy maneuvering of vehicles, especially the larger trucks and coaches.
It is against this background and the problems and difficulties associated therewith, that the present invention has been developed.